1. Field of the Invention
The present invention relates to a lens driving apparatus, a lens barrel, and an optical apparatus.
2. Description of the Related Art
Conventionally, a lens driving apparatus that moves a lens group by using a stepping motor when performing a variable power operation and a focusing operation has been mounted on a lens barrel used as an interchangeable lens or the like in an optical apparatus, for example, a digital still camera and a video camera. Such a lens driving apparatus that moves a guide that guides a movement of the lens during moving back and forth of the lens and a lens holding frame without a wobble between them is desired. Japanese Patent Application Publication No. 6-174992 discloses a configuration in which a regulation of a rotation blur is achieved by a rack configuration that has interposing teeth that interpose a motor screw in a rack. Additionally, Japanese Patent Application Publication No. 2007-298718 discloses a configuration in which the regulation of the rotation blur is achieved by a configuration in which the rack is pressed against the motor screw.
However, in the conventional arts disclosed in the aforementioned patent documents, there is a possibility that a stable balance cannot be configured when, for example, an attitude is changed in a case where the mass of the lens group is large, thereby to cause a tilt of the lens group and the rotation blur. Additionally, it may affect an optical property, for example, an image shake, as a result. For example, Japanese Patent Application Publication No. 6-174992 discloses a configuration in which the interposing teeth that interpose the motor screw are provided in the rack, an angle is given to the interposing teeth, and an energizing force is applied to the lens group. Here, it is necessary to increase an interposing force or increase the angle of the interposing teeth in order to increase the energizing force to correspond to the mass of the lens group. Accordingly, there is a problem in which a load that obstructs the rotation of the motor becomes high in many cases. Although the disclosure of Japanese Patent Application Publication No. 2007-298718 enables decreasing the load to the motor compared with the disclosure of Japanese Patent Application Publication No. 6-174992, both disclosures require increasing the energizing force of the rack according to the increase of the mass of the lens group, and thus, it is difficult to avoid the similar problem to be solved.